why it is necessary to monitor your sites permanently on marketing
Since some months we are running a test on urltrends.com. They show us a lot of graphics for different webpresence services (search machines, blogs, social bookmarks) that indicates the popularity of the website. But we came to the conclusion that it is too hectic to be 100 believable and otherwise that it shows clearly that if you don't monitor permanently your webpresence if you have serious business on the web that you can be in for some big surprises.
No way you could lose more than 8000 links in one month for example and so there are many more examples.
You should also always double check this kind of tools and services with some others if you want more than voodoo-science.